In recent years, so-called jet-propulsion personal watercraft have been widely used in leisure, sport, rescue activities, and the like. Personal watercraft are generally configured to have a propulsion pump which is a propulsion device that pressurizes and accelerates water sucked from a water intake provided on a hull bottom surface and ejects it rearward from an outlet port. As a result, the personal watercraft is propelled.
In the jet-propulsion personal watercraft, a steering nozzle provided behind the outlet port of the propulsion pump is pivoted either to the right or to the left, to change the ejection direction of the water from rearward to the right or to the left, thereby turning the watercraft to the right or to the left.
The personal watercraft which is represented by the above jet-propulsion personal watercraft is typically equipped with a multi-cylinder engine configured to drive a propulsion device such as the propulsion pump.
In the above personal watercraft, the water intake of the propulsion pump is sometimes exposed in air for a moment while the watercraft is skipping on water waves. In this case, a load applied to the engine is significantly reduced for a moment, causing an over revolution of the engine. The over revolution is unfavorable to the engine. To avoid occurrence of the over revolution of the engine, some personal watercraft are equipped with an over revolution inhibiting system configured to omit both of or either one of fuel feeding and ignition, as disclosed in Japanese Laid-Open Patent Application Publication No. 2000-345873.
However, if the over revolution inhibiting system equipped in the personal watercraft is activated, uncombusted gas is sometimes left in a muffler of an exhaust system of the engine. The uncombusted gas left in the muffler may be combusted, causing an “after fire.”
Undesirably, the after fire generates a large noise and applies an unwanted pressure to the muffler and to the exhaust system of the engine.